Pharmaceutics 1 Lecture Notes PDF

Field of Pharmacy Sciences Bachelor of Pharmacy-PharmD (Clinical Pharmacy Program) Pharmaceutics 1 (PPH203) Lecture: 2 ( Solutions) Assoc. Prof. : Mohammad Yehia Date: 10 /10 /2023  Pharmaceutics 1 Liquid Dosage forms 1. Pharmaceutical Solutions Classificat...

Field of Pharmacy Sciences Bachelor of Pharmacy-PharmD (Clinical Pharmacy Program) Pharmaceutics 1 (PPH203) Lecture: 2 ( Solutions) Assoc. Prof. : Mohammad Yehia Date: 10 /10 /2023  Pharmaceutics 1 Liquid Dosage forms 1. Pharmaceutical Solutions Classification of Liquid Dosage form According to Dispersed System 1- Monophasic system: Solutions 2- Polyphasic system: 2.1. Colloids 2.2. Suspensions 2.3. Emulsions According to the Route of Administration 1. Oral: Syrups, elixirs, drops 2. In mouth and throat: Mouth washes, gargles and throat sprays. 3. In body cavities: Douches, enemas (rectal), ear drops (Otic) and nasal solutions. 4. On body Surfaces (Topical): Collodions, liniments and lotions. 5. Parenteral products. 6. Ophthalmic (ocular) products  Ingredients of pharmaceutical solutions: Vehicles Def. “They are solvents in which active and inactive ingredients are dissolved.” The choice of vehicles depends on: - The intended use of the preparation - The nature and physicochemical properties of the active ingredients. # Although WATER is the most commonly used solvent, different non-aqueous vehicles can be used. Thus, according to the vehicle type they can be classified to: 1. Aqueous solutions: 1.1. Water. 1.2. Aromatic water. 1.3. Extracts: infusion and decoction. 2. Non-aqueous solutions: 2.1. Alcoholic or hydroalcoholic solutions, e.g. elixirs and spirits. 2.2. Ethereal solutions, e.g. the collodions. 2.3. Glycerin solutions, e.g. the glycerites. 2.4. Oleaginous solutions e.g. the liniments, medicated oils, oleo-vitamins.  Ingredients of pharmaceutical solutions: Viscosity enhancement agents It may be difficult for aqueous-based topical solutions to remain in place on the skin or in the eyes for any significant time (low viscosity) Gelling agents can be used to increase the apparent viscosity of the product. Preservatives: They are substances added to the preparation to prevent the growth of microorganisms such as bacteria and fungi.  Ingredients of pharmaceutical solutions: Antioxidants: The decomposition of pharmaceutical products by oxidation can be controlled by the addition of antioxidants or reducing agents. Sweetening agents Low molecular weight carbohydrates, and in particular sucrose, are the most widely used sweetening agents. Flavoring agents Def.: They are substances added to preparations that contain drugs with unpleasant taste. This is particularly useful in pediatric formulation to ensure patient compliance. Colors To improve the attractiveness of the product, it is often useful to include a color associated with that flavor. The presence of a strongly colored degradation product, (which does not affect the use of the product) may be masked by the use of a suitable color.  Ingredients of pharmaceutical solutions: Types of solutions according to the type of solvent in which the active ingredients are dissolved Non-aqueous Aqueous solution solutions Water: The solvent most widely used as a vehicle for pharmaceutical products. It is physiological compatible of no toxicity. It is also very cheap, odorless and colorless. It possesses a high dielectric constant, which is essential for ensuring the dissolution of a wide range of ionizable materials.  Types of pharmaceutical water: Potable water Purified Water for injection water Potable water (tap water) It is water freshly drawn from the mains system and which is suitable for drinking. Not used for preparation of medical preparations (only used as stock for the production of other grades of water). Disadv. Its chemical purity may vary with time and location. possible chemical incompatibilities between dissolved solids and the medicinal agents being added. Purified water This grade of water is normally used for the manufacture of all non-sterile liquid dosage forms. It contains fewer solid impurities than tap water. Methods of preparation of Purified water Ion Reverse Distillation exchange osmosis  Distillation The tap water (with its contaminants) is boiled, the pure water turns into steam and is captured and cooled and thus becomes purified water(distilled water). The left behind portion contains all of the contaminants. Contaminants found in water are inorganic minerals, metals (with very high melting point) The first portion of aqueous distillate (10-20%) must be discarded (contains foreign volatile substances) The last portion of water (10%) remaining must also be discarded to prevent decomposition of the remaining solid impurities to volatile substance that would contaminate the previously collected portion. Ion exchange In this method, water passes through a column of cation and anion exchangers. They consist of water-insoluble synthetic resins of high molecular weight. The resins are of two types: - The cations (acid exchangers), exchange the cations in the tap water with hydrogen ion from the resin - The anions (base exchange resins), permit the removal of anions found in the tap water.  Ion exchange is done as the following: Cation-exchange resin: Formula: R−H Anion-exchange resin: Formula: R−OH Advantages of ion exchange over distillation. - Requirement of heat is eliminated - Ease of operation - Minimal maintenance - Simple and can be mobile facility Disadvantages of ion exchange Does not effectively remove pyrogens or bacteria. The water obtained by this method is called “deionized” or “demineralized” water  Reverse osmosis Osmosis is defined as the spontaneous diffusion of solvent from a solution of low solute concentration (or a pure solvent) into a more concentrated one, through a semipermeable membrane. The flow of the water can be reversed by applying a pressure greater than the osmotic pressure. The purified water obtained is called (permeate). The retained water which contains the concentrated contaminants is called the reject (or concentrate) stream. The amount of pressure required depends on the salt concentration of the feed water. The more concentrated the feed water, the more pressure is required.  Aromatic waters They are aqueous solutions of volatile materials, They are used mainly for their flavoring properties, although they might be used for their medicinal effect. Examples include peppermint water and anise water, which also have carminative properties, and chloroform water, which also acts as a preservative. They are usually manufactured as concentrated waters and are then diluted in the final preparation (1:40) Aromatic waters should be freshly prepared in small suitable quantity and protected from light and heat. They suffer from deterioration (cloudy appearance) with time due to: Volatilization - decomposition - mold growth.  Methods of preparations Distillation Solution - Triturate 1 part or the specified - The odoriferous drug is distilled amounts of the odouriferous in a suitable still, with a sufficient substance with 15 parts of talc quantity of potable water, until the powder. specified volume of (A.W) has been - Gradually add recently boiled and cooled distilled water, in collected. successive small portions - The (A.W) is set aside for 12 - Agitate for 15 minutes. hours, filtered if necessary. - Set aside for 12 hours. - Cohobation: If the (V.O) in - Filter and pass sufficient amount distillate is present in small quantities of the water through the filter to the distillate is returned several times produce 1000 parts of almost clear to be redistilled with more fresh drug. filtrate.  Sweet or other viscid aqueous solution Syrups Linctuses Mucilages Jellies Syrup are concentrated solutions of sugar or sweetening agents such as sucrose in water or other aqueous liquid (nearly saturated). - Syrups are characterized by sweetness and viscosity. - When the syrup is swallowed, only a portion of the dissolved drug actually makes contact with the taste buds Glycogenic substance: e.g glycerol or sorbitol (not for diabetic patients) They retard crystallization of sucrose or to increase solubility of other drugs Non-glycogenic: e.g methylcellulose, hydroxyethylcellulose are used (Viscosity) To add the required sweetness, artificial sweeteners as saccharin sodium, cyclamate sodium, aspartam must be added.  Artificial sweeteners not metabolized by the human body, so it contributes no energy to the diet and is considered a nonnutritive sweetener. Saccharin sodium It is about 300–400 times as sweet as sucrose but has a bitter or metallic aftertaste Cyclamate sodium with about 30 times the sweetening power of sucrose It has no aftertaste Aspartame It is 200 times as sweet as sucrose Aspartame is the closest to sugar's taste profile among approved artificial sweeteners.  Types of Syrups: Simple syrup: which contains only sugar with water. Flavored syrups: It contains flavor (with no active ingredients) Medicated syrups: are syrups containing active ingredients. Example: Simple Syrup EP (W/W) USP and BP (W/V) R/ Sucrose 667 gm 850 gm Purified Water ad 1000 gm 1000 ml Additives that may present in the syrups: A- Flavoring agents (orange oil, vanillin, etc.,) B- Coloring agents (green with mint, brown with chocolate, and so on) C- Antimicrobial preservatives Syrups No need for If diluted Free water sugar Nearly Preservatives excellent for saturated No free water mold growth Preservative required How to calculate the amount of preservative required for preparation? The amount used of the preservative depends on the amount of free water (sugar concentration less than 85 %w/v). Example How much benzoic acid should be added to 60% w/v sucrose solution? - The amount of water which preserved by this amount of sugar: The free water remains = 100 – 70.6 = 29.4 ml The amount of benzoic acid required for 29.4 ml (conc. 0.1 %w/v) 1- Calculate the amount of sorbic acid required to be used as preservative for the following formula: Rx Codeine phosphate 0.06 gm Sorbic acid Q.S Sucrose 30 gm Water ad 90 ml 2- Calculate the amount of ethanol required to be used as preservative for the following formula: Rx Ephedrine HCl 0.06 gm Ethanol (70%w/v) Q.S Sucrose 660 gm Water ad 1000 ml